Auto merge of #115910 - eduardosm:lang-fns-target-features, r=cjgillot

Prevent using `#[target_feature]` on lang item functions

Fixes rust-lang/rust#109411 and also prevents from using `#[target_feature]` on other `fn` lang items to mitigate the concerns from rust-lang/rust#109411 (comment).

Author: bors